期刊文献+
共找到14篇文章
< 1 >
每页显示 20 50 100
用于脑卒中病灶分割的具有注意力机制的校正交叉伪监督方法
1
作者 周妍 李阳 《计算机应用》 CSCD 北大核心 2024年第6期1942-1948,共7页
脑部病变的自动分割为脑卒中患者的及时诊治和诊疗方案的制定提供了可靠的依据,但获取大规模标记数据昂贵且耗时。半监督学习(SSL)方法通过利用大量的未标记图像和有限的标记图像缓解这一问题。针对SSL中伪标签存在噪声,以及现有的三维(... 脑部病变的自动分割为脑卒中患者的及时诊治和诊疗方案的制定提供了可靠的依据,但获取大规模标记数据昂贵且耗时。半监督学习(SSL)方法通过利用大量的未标记图像和有限的标记图像缓解这一问题。针对SSL中伪标签存在噪声,以及现有的三维(3D)网络缺乏聚焦较小目标的能力这2个问题,提出一种半监督方法,即用于脑卒中病灶分割的具有注意力机制的校正交叉伪监督方法RPE-CPS(Rectified Cross Pseudo Supervision with Project&Excite modules)。首先,将数据输入2个结构相同但初始化不同的3D U-Net分割网络,将得到的伪分割图用于交叉监督训练分割网络,充分利用伪标签数据扩展训练集,并鼓励不同初始化网络对同一输入图像的预测之间具有较高的相似性;其次,设计一种基于不确定性估计的交叉伪监督方法的校正策略,以降低伪标签中的噪声影响;最后,在3D U-Net分割网络中,为提高小目标类的分割性能,将投影-激发(PE)模块添加至每一个编码器模块、解码器模块和瓶颈模块之后。为验证所提方法的有效性,在合作医院急性缺血性脑卒中(AIS)数据集和缺血性脑卒中病灶分割挑战赛(ISLES2022)数据集上分别进行评估实验。实验结果表明,在仅使用训练集中20%的标记数据时,在公开数据集ISLES2022上Dice相似系数(DSC)、95%豪斯多夫距离(HD95)和平均表面距离(ASD)分别达到了73.87%、6.08 mm和1.31 mm;在AIS数据集上DSC、HD95和ASD分别达到了67.74%、15.38 mm和1.05 mm。与先进的半监督方法不确定性校正金字塔(URPC)相比,DSC分别提升了2.19和3.43个百分点。所提方法可以有效地利用未标记数据提高分割精度,优于其他半监督方法,并具有鲁棒性。 展开更多
关键词 医学影像 脑卒病灶分割 半监督学习 注意力机制 不确定性估计
下载PDF
基于注意力增强U-Net的脑卒中病灶分割 被引量:1
2
作者 王一诺 张俊然 +1 位作者 刘彦 李家琛 《计算机工程与设计》 北大核心 2022年第8期2268-2274,共7页
基于卷积神经网络的分割模型可以自主学习特征,精确快速分割病灶,为缺血性卒中临床救治提供客观高效的决策支持。针对现有研究由于复杂的算法流程和模型结构导致分割时间大量增加,以及U-Net缺乏对特征通道和空间信息的关注,不能很好地... 基于卷积神经网络的分割模型可以自主学习特征,精确快速分割病灶,为缺血性卒中临床救治提供客观高效的决策支持。针对现有研究由于复杂的算法流程和模型结构导致分割时间大量增加,以及U-Net缺乏对特征通道和空间信息的关注,不能很好地适应形态位置各异的病灶等问题,提出基于通道和空间注意力增强模块CSA的U-Net,利用一维卷积和膨胀卷积,分别获得高效的通道间依赖关系和感受野更广的空间注意力。在ISLES 2018数据集上进行验证,实验结果表明,CSA提升了U-Net的分割效果,分割性能优于其它几种U-Net的变体。 展开更多
关键词 缺血性脑卒病灶分割 医学图像分割 语义分割 U型网络 注意力机制
下载PDF
基于中位分割碎片合并的特征挖掘云平台设计 被引量:5
3
作者 廉文武 《科技通报》 北大核心 2014年第6期97-99,共3页
为有效精确地挖掘海量数据流特征,提出采用数据集中位分割和冗余数据碎片合并的方法设计决策树并构建云平台数据特征挖掘模型。传统的云平台下数据挖掘中对碎片信息不做处理,使文本碎片成几何级增长,导致有用信息的丢失。通过挖掘冗余... 为有效精确地挖掘海量数据流特征,提出采用数据集中位分割和冗余数据碎片合并的方法设计决策树并构建云平台数据特征挖掘模型。传统的云平台下数据挖掘中对碎片信息不做处理,使文本碎片成几何级增长,导致有用信息的丢失。通过挖掘冗余信息中符合挖掘条件的碎片特征,使用KD树进行数据挖掘索引,在迭代过程中,对数据进行层进中位分割,并结合碎片合并技术,构建数据挖掘云平台模型,对中位数进行维度匹配分箱,使数据的挖掘和传输率最大限度地得到利用。仿真实验证明了采用碎片合并的方法能有效提取冗余碎片中的有用特征信息,数据挖掘性能得到大幅度提升,在数据信息提取和管理中具有很好的推广意义。 展开更多
关键词 分割 碎片合并 特征挖掘 云平台
下载PDF
基于双向循环U-Net模型的脑卒中病灶分割方法
4
作者 贾小慧 张雪英 +3 位作者 王夙喆 回海生 李凤莲 张华 《太原理工大学学报》 CAS 北大核心 2022年第6期1127-1133,共7页
脑卒中具有极高致残率和致死率,研究脑卒中病变的自动识别和分割方法具有重要的临床意义。提出一种基于双向循环U-Net(BIRU-Net)模型的病灶分割方法。首先,引入循环神经网络结构,将改进的注意力卷积门递归单元(ACGRU)替代U-Net中的部分... 脑卒中具有极高致残率和致死率,研究脑卒中病变的自动识别和分割方法具有重要的临床意义。提出一种基于双向循环U-Net(BIRU-Net)模型的病灶分割方法。首先,引入循环神经网络结构,将改进的注意力卷积门递归单元(ACGRU)替代U-Net中的部分卷积层,使分割模型既适用于小规模标注的医学影像数据集,又具有长时记忆特性;其次,采用双路融合训练机制,将单一视面的正向、反向的切片数据同时输入BIRU-Net,并在模型前向传播过程实现双向特征融合,有效利用了切片序列的双向依赖特性。最后,将各单一视面的分割结果进行再融合,有效利用了数据的空间上下文信息。对于ATLAS数据集的实验结果表明,所提方法的DSC值达到了62.58%,与现阶段的其他方法相比,本文的方法能较为准确地分割出病灶区域。 展开更多
关键词 深度学习 脑卒病灶分割 CGRU U-Net 双向特征融合 多视面融合
下载PDF
一种基于局部与全局表征交叉耦合的脑卒中病灶分割网络模型
5
作者 倪波 柯亨进 刘志远 《中南民族大学学报(自然科学版)》 CAS 北大核心 2023年第6期828-838,共11页
由于脑卒中严重程度不同,病灶位置、形状和面积有较大差异,导致目前基于深度学习的分割方法仍还不够理想.针对脑卒中病灶特征,提出了一种新的U型分割网络,该网络的编码器是一个结合Transformer和卷积网络的双分支混合架构,该结构特点是... 由于脑卒中严重程度不同,病灶位置、形状和面积有较大差异,导致目前基于深度学习的分割方法仍还不够理想.针对脑卒中病灶特征,提出了一种新的U型分割网络,该网络的编码器是一个结合Transformer和卷积网络的双分支混合架构,该结构特点是在构建图像层次化特征过程中将基于Transformer的全局特征和基于卷积网络的局部特征进行交叉学习,促进编码器在训练和推理过程中将两种风格的特征相互增强.此外,为了增强小目标、弱边缘的特征表达,构建了合并模块将编码器得到的两种风格的层次化特征进行融合,并将融合后特征输送到一个级联的上采样器中预测病灶区域,以及设计了一个结合Dice函数和Focal函数的损失函数用以缓解小病灶区域造成的前景与背景数据之间的数据不平衡问题.所提出的方法在一个开源脑卒中数据集进行了验证,与其他相关方法相比,所提出的方法在分割精度、效率等方面均表现出较好的性能. 展开更多
关键词 脑卒病灶分割 卷积神经网络 自注意力模型 U型网络
下载PDF
连续量信息表决策值的离散化方法 被引量:7
6
作者 高赟 侯媛彬 《西安科技大学学报》 CAS 北大核心 2004年第4期486-491,共6页
在用粗糙集理论解决连续系统的问题时,要求信息表必须是离散值.在对由连续量构成的信息表离散化时,首先要对决策属性的值域进行离散化。文中针对这一问题提出了3种确定离散化区间的方法,即经验分割法、等频分割法和等距分割法;又提出了... 在用粗糙集理论解决连续系统的问题时,要求信息表必须是离散值.在对由连续量构成的信息表离散化时,首先要对决策属性的值域进行离散化。文中针对这一问题提出了3种确定离散化区间的方法,即经验分割法、等频分割法和等距分割法;又提出了2种求区间离散值的算法,即区间重心法和区间值平均法,并通过算例验证这些算法均是可行的,其中等距分割法中的区间值平均法效果最为满意。 展开更多
关键词 粗糙集 信息表 决策属性值 离散化 等距分割 知识获取
下载PDF
Stratigraphic Division Based on Minor Elements in the Sediment Core Q43 from the Outer Shelf of the East China Sea:Approached Through Correspondence Analysis and Fuzzy Cluster Analysis 被引量:2
7
作者 LINXiaotong LIWeiran DUShujie 《Journal of Ocean University of China》 SCIE CAS 2005年第2期131-136,共6页
The multivariate statistical techniques, principal component analysis, Q-modefactor analysis, correspondence analysis and fuzzy C-means clustering were applied to analyzing thedatasets of minor element concentrations ... The multivariate statistical techniques, principal component analysis, Q-modefactor analysis, correspondence analysis and fuzzy C-means clustering were applied to analyzing thedatasets of minor element concentrations in sediment samples of a core collected from the outershelf of the East China Sea. According to the analysis results, the sediment core Q43 can be dividedinto three strata with different features in minor elements. The first stratum (unit Ⅰ) ischaracterized by higher concentrations of Ⅴ, Cr, Cd and Sc, which are active and inactive elements.The second stratum (unit Ⅱ) is controlled by ultrastable elements Ⅴ, Ti, Cr, Th, Sc, Pb, etc. Thethird stratum (unit Ⅲ) is dominated by Ni, Co, Ba, Rb and Mn, which are authigenic andvolcanogenic elements. The geochemical features of the core Q43 show environmental changes in thedepositional process from the Late Pleistocene to Holocene. 展开更多
关键词 East China Sea stratigraphic division GEOCHEMISTRY multivariatestatistical techniques
下载PDF
A New Word Detection Method for Chinese Based on Local Context Information 被引量:1
8
作者 曾华琳 周昌乐 郑旭玲 《Journal of Donghua University(English Edition)》 EI CAS 2010年第2期189-192,共4页
Finding out out-of-vocabulary words is an urgent and difficult task in Chinese words segmentation. To avoid the defect causing by offline training in the traditional method, the paper proposes an improved prediction b... Finding out out-of-vocabulary words is an urgent and difficult task in Chinese words segmentation. To avoid the defect causing by offline training in the traditional method, the paper proposes an improved prediction by partical match (PPM) segmenting algorithm for Chinese words based on extracting local context information, which adds the context information of the testing text into the local PPM statistical model so as to guide the detection of new words. The algorithm focuses on the process of online segmentatien and new word detection which achieves a good effect in the close or opening test, and outperforms some well-known Chinese segmentation system to a certain extent. 展开更多
关键词 new word detection improved PPM model context information Chinese words segmentation
下载PDF
Apriori and N-gram Based Chinese Text Feature Extraction Method 被引量:4
9
作者 王晔 黄上腾 《Journal of Shanghai Jiaotong university(Science)》 EI 2004年第4期11-14,20,共5页
A feature extraction, which means extracting the representative words from a text, is an important issue in text mining field. This paper presented a new Apriori and N-gram based Chinese text feature extraction method... A feature extraction, which means extracting the representative words from a text, is an important issue in text mining field. This paper presented a new Apriori and N-gram based Chinese text feature extraction method, and analyzed its correctness and performance. Our method solves the question that the exist extraction methods cannot find the frequent words with arbitrary length in Chinese texts. The experimental results show this method is feasible. 展开更多
关键词 Apriori algorithm N-GRAM Chinese words segmentation feature extraction
下载PDF
An approach to offline handwritten Chinese character recognition based on segment evaluation of adaptive duration
10
作者 李国宏 施鹏飞 《Journal of Zhejiang University Science》 CSCD 2004年第11期1392-1397,共6页
This paper presents a methodology for off-line handwritten Chinese character recognition based on mergence of consecutive segments of adaptive duration. The handwritten Chinese character string is partitioned into a s... This paper presents a methodology for off-line handwritten Chinese character recognition based on mergence of consecutive segments of adaptive duration. The handwritten Chinese character string is partitioned into a sequence of consecutive segments, which are combined to implement dissimilarity evaluation within a sliding window whose durations are determined adaptively by the integration of shapes and context of evaluations. The average stroke width is estimated for the handwritten Chinese character string, and a set of candidate character segmentation boundaries is found by using the integration of pixel and stroke features. The final decisions on segmentation and recognition are made under minimal arithmetical mean dissimilarities. Experiments proved that the proposed approach of adaptive duration outperforms the method of fixed duration, and is very effective for the recognition of overlapped, broken, touched, loosely configured Chinese characters. 展开更多
关键词 Handwritten Chinese character Segmentation boundary SEGMENT DURATION
下载PDF
Establishing and validating a spotted tongue recognition and extraction model based on multiscale convolutional neural network 被引量:7
11
作者 PENG Chengdong WANG Li +3 位作者 JIANG Dongmei YANG Nuo CHEN Renming DONG Changwu 《Digital Chinese Medicine》 2022年第1期49-58,共10页
Objective In tongue diagnosis,the location,color,and distribution of spots can be used to speculate on the viscera and severity of the heat evil.This work focuses on the image analysis method of artificial intelligenc... Objective In tongue diagnosis,the location,color,and distribution of spots can be used to speculate on the viscera and severity of the heat evil.This work focuses on the image analysis method of artificial intelligence(AI)to study the spotted tongue recognition of traditional Chinese medicine(TCM).Methods A model of spotted tongue recognition and extraction is designed,which is based on the principle of image deep learning and instance segmentation.This model includes multiscale feature map generation,region proposal searching,and target region recognition.Firstly,deep convolution network is used to build multiscale low-and high-abstraction feature maps after which,target candidate box generation algorithm and selection strategy are used to select high-quality target candidate regions.Finally,classification network is used for classifying target regions and calculating target region pixels.As a result,the region segmentation of spotted tongue is obtained.Under non-standard illumination conditions,various tongue images were taken by mobile phones,and experiments were conducted.Results The spotted tongue recognition achieved an area under curve(AUC)of 92.40%,an accuracy of 84.30%with a sensitivity of 88.20%,a specificity of 94.19%,a recall of 88.20%,a regional pixel accuracy index pixel accuracy(PA)of 73.00%,a mean pixel accuracy(m PA)of73.00%,an intersection over union(Io U)of 60.00%,and a mean intersection over union(mIo U)of 56.00%.Conclusion The results of the study verify that the model is suitable for the application of the TCM tongue diagnosis system.Spotted tongue recognition via multiscale convolutional neural network(CNN)would help to improve spot classification and the accurate extraction of pixels of spot area as well as provide a practical method for intelligent tongue diagnosis of TCM. 展开更多
关键词 Spotted tongue recognition and extraction The feature of tongue Instance segmentation Multiscale convolutional neural network(CNN) Tongue diagnosis system Artificial intelligence(AI)
下载PDF
建设在未来20年 提供对称1Gbps服务的DOCSIS网络
12
作者 阿哈姆·阿版纳 《世界宽带网络》 2012年第12期52-53,共2页
一简介 随着带宽需求指数型地增长.有线运营商需要设计并升级他们的网络来满足未来带宽需求。需要考虑多种因素,包括成本、频谱规划、运营、技术挑战、前端设备还有用户的体验质量等,另外还要考虑好各步骤适当的实施顺序,获得一个... 一简介 随着带宽需求指数型地增长.有线运营商需要设计并升级他们的网络来满足未来带宽需求。需要考虑多种因素,包括成本、频谱规划、运营、技术挑战、前端设备还有用户的体验质量等,另外还要考虑好各步骤适当的实施顺序,获得一个最优化的网络.从而实现一个灵活的网络拓扑,提供最大的容量和最少的成本。 展开更多
关键词 DOCSIS 流量需求 中分割 分割
原文传递
Rupture segmentation and slip partitioning of the mid-eastern part of the Kunlun Fault,north Tibetan Plateau 被引量:42
13
作者 LI ChenXia XU XiWei +5 位作者 WEN XueZe ZHENG RongZhang CHEN GuiHua YANG Hu AN YanFen GAO Xiang 《Science China Earth Sciences》 SCIE EI CAS 2011年第11期1730-1745,共16页
The Kunlun Fault, an active fault on the border between the Bayan Har and Kunlun-Qaidam blocks, is one of the major left lateral strike-slip faults in the Tibetan Plateau. Previous research has not reached a consensus... The Kunlun Fault, an active fault on the border between the Bayan Har and Kunlun-Qaidam blocks, is one of the major left lateral strike-slip faults in the Tibetan Plateau. Previous research has not reached a consensus on agreeable slip rates along much of its length and the slip rate gradient along the eastern part, both of which play critical roles in a range of models for the eastward extrusion and thickened crust of the Tibetan Plateau. New slip rates have been determined at sites along the eastern part of the Kunlun Fault by dating deposits and measuring atop displaced fluvial terrace risers. Field investigations and interpretation of satellite images reveal geometrical features of the fault and the late Quaternary offset, new earthquake ruptures and surface-rupturing segmentation, from which long-term slip rates and earthquake recurrence intervals on the fault are estimated. The tectonic geomorphology method has determined that the long-term horizontal slip rates on the Tuosuohu, Maqin and Ma- qu segments from west to east are 11.2±1, 9.3±2, and 4.9±1.3 mm/a while their vertical slip rates are 1.2±0.2, 0.7±0.1, and 0.3 mm/a in the late Quaternary. Results indicate that the slip rates regularly decrease along the eastern -300 km of the fault from 〉10 to 〈5 mm/a. This is consistent with the decrease in the gradient such that at the slip rate break point is at the triple point intersection with the transverse fault, which in turn is transformed to the Awancang Fault. The vector decomposition for this tectonic transformation shows that the western and eastern branches of the Awancang Fault fit the slip-partitioning mode. The slip rate of the southwestern wall is 4.6 mm/a relative to the northeastern wall and the slip direction is 112.1°. The mid-eastern part of the Kunlun Fault can be divided into three independent segments by the A'nyemaqen double restraining bend and the Xigongzhou intersection zone, which compose the surface rupture segmentation indicators for themselves as well as the ending point of the 1937 M7.5 Tuosuohu earthquake. The average recurrence interval of the characteristic earthquakes are estimated to be 500-1000 a, respectively. The latest earthquake ruptures occurred in AD 1937 on the western Tuosuohu segment, as compared to -514-534 a BP on the Maqin segment, and -1055 to 1524 a BP on the Maqu segment. This may indicate a unidirectional migration for surface rupturing earthquakes along the mid-eastern Kunlun Fault related to stress triggered between these segments. Meanwhile, the long-term slip rate is obtained through the single event offset and the recurrence interval, which turn out to be the same results as those determined by the offset tectonic geomorphology method, i.e., the decreasing gradient corresponds to the geometrical bending and the fault's intersection with the transverse fault. Therefore, the falling slip rate gradient of the mid-eastern Kunlun Fault is mainly caused by eastward extension of the fault and its intersection with the transverse fault. 展开更多
关键词 mid-eastern Kunlun Fault slip rate surface rupture segmentation slip partition PALEOEARTHQUAKE Tibetan Plateau
原文传递
Chinese to Braille Translation Based on Braille Word Segmentation Using Statistical Model 被引量:2
14
作者 王向东 杨阳 +3 位作者 张金超 姜文斌 刘宏 钱跃良 《Journal of Shanghai Jiaotong university(Science)》 EI 2017年第1期82-86,共5页
Automatic translation of Chinese text to Chinese Braille is important for blind people in China to acquire information using computers or smart phones. In this paper, a novel scheme of Chinese-Braille translation is p... Automatic translation of Chinese text to Chinese Braille is important for blind people in China to acquire information using computers or smart phones. In this paper, a novel scheme of Chinese-Braille translation is proposed. Under the scheme, a Braille word segmentation model based on statistical machine learning is trained on a Braille corpus, and Braille word segmentation is carried out using the statistical model directly without the stage of Chinese word segmentation. This method avoids establishing rules concerning syntactic and semantic information and uses statistical model to learn the rules stealthily and automatically. To further improve the performance, an algorithm of fusing the results of Chinese word segmentation and Braille word segmentation is also proposed. Our results show that the proposed method achieves accuracy of 92.81% for Braille word segmentation and considerably outperforms current approaches using the segmentation-merging scheme. 展开更多
关键词 Chinese Braille word segmentation perceptron algorithm TP 391.1 A
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部